Silicon article.



"Toallt whom it may concern:

STATEs PATENT orrro. A

worms 3. ALLEN, or NIAGARA FALLS, new YonK, ASSIGNOB are THE oaasoaunnum (DMZEMY, or maestro. FALLS, new YORK, a CORPORATION or PENNSYLVANIA.

srmoon ARTICLE.

Be it known that I, THOMAS B. ALLEN, a

resident of Niagara Falls, Niagara county,

State of New ork, have invented anew and useful Improvement in SiliconArticles,

, f which thefollo'wing is a full, clear, and exact description. f

This invention has relation to a new and useful improvement in vsilicon articles.

Heretofore, the production of silicon articles casting molten metal into the desired shape has been attended with very great difficulties, which have been so great as to practically prevent the formation of suitable articles. '1 The main, difiiculties in casting the ordinary molten metal have been, first, that the cast metal is very spongy and orous, being filled with blow holes and pin oles; second, that the cast article is mechanically unsound, this being largely occasioned by the presence of flow marks due to the lapping of the metal which causes agent.

folds in the surfaces of the cast silicon; and third, that the cast metal is rather coarsely crystalline.

I have discovered that electric furnace silicon and silicon alloys and compounds contain dissolved silicon dioxid and dissolved nitrogen and oxygen, and that by removing these substances, I am able to obtain castings which are stronger, denser and more perfect than any castings so far obtained. I have further discovered that I can obtain the improvements and removethe impurities by means of a large number of substances, such as the alkali metals, the alkaline earth metals, magnesium, vanadium, titanium, aluminum, boron, etc., and in general, any element which has a combining heat with the impurities, which is greater than that of silicon. To-obtain especially advantageous results, I preferably use a material, such as calcium, magnesium, vanadium, etc., which, besides acting as a deoxidizing agent, can act as a denitrogenizing I may, however, also add an element, such as sodium, to remove the oxygen or oxide, and a substance, such as vanadium, to remove the nitrogen or nitrids.

I will now describe a preferred method of making an article embodying my invention, with reference to the use of magnesium. preferably tap the molten silicon from the electric furnace in Which it is made into a graphitecrucible, and place this crucible in a coke or oil burning crucible furnace. I then beat the silicon for about one to two hours, having preferably placed a layer of coke on the surface of the silicon to prevent loss by oxidation and volatilization. When the silicon is in a very fluid condition, I remove the crucible from the furnace, skim oil the coke and add the magnesium to the molten silicon in the form of a fine powder, or in small lumps, by means of an implement commonly called a phosphorizer. I have found that I can obtain the desired results by adding from one-half per cent. to three per cent. magnesium, and I contemplate adding only such a quantity of, this substance which will combine with the impurities and pass 03 to the surface of the silicon as a slag. The magnesium silicate formed when magnesium is used is readily fusible and comes to the surface of the fused silicon. When the silicon shows no-further reaction due to magnesium and is in a quiescent condition,I preferably pour it from the bottom of the crucible in order toprevent any of the slag from the surface getting into the molten silicon- In making the mold of the desired shape, for'thesilicon article, I prefer to use what is commonly known as a dry sand mold and to coat the surfaces of this mold with which the molten silicon comes in contact with talc. I have further found it desirable to pour the metal into the mold throu h a gate entering at the bottom of the mold and to use a comparatively large riser, so that the casting cools under considerable fluid pressure. By this means, I aid the production of dense sound castings. The articles produced in this manner are mechanically sound and show a marked absence of blow holes and flow marks. The metal crystallizes in very fine crystals and shows a marked interpenetration of the same which causes articles produced to have considerable mechanical strength.

The cast articles are adapted for use for various purposes, being particularly useful as chemical ware on account of their remarkable acid-resisting properties. They are made in the form of pipes, evaporating vessels, receivers, crucibles and pump parts for the concentration and conveyance of acids and acid gases. I do not, however, limit myself to these particular articles.

' It will be evident to others skilled in the art of making castings that I may make changes in theldescribed method, without departing from the spirit of the invention. Further, by the term silicon used in the following claims, I I mean to include the alloys and compounds in which silicon is the principal constituent art. 1

' 'llhe novel method herein described forms the subject matter of my. Patent No. 1,037,713, dated Se tember 3, 1912,. for

method of making si won articles.

ties, and having-a fine crystalline structure,

substantially as described. I

As a new article of manufacture, a cast article having silicon as its principal con-.

novaaeo stituent vpart and being substantially free from nitrogenous and 'oxygenous impurities and bein of substantially" uniform density throng out its mass, substantially as described.

4:- As a new article of manufacture, a cast article having silicon as its principal con stituent part, the casting having an even i crystalline structure and being substantially free from nitrogenous and oxy enous i1'n' gurities, and being of stantia y uniform ensity'throughdut' its mss.f I 5. As anew article of manufacture, a cast article having silicon as its principal constituent part, the casting ,having a fine 4 crystalline structure and being substantially free from silicon dioxid; substantially as described. In testimony whereof, I have hereunto set my hand. v v

'rr-ros. 1e. ALLEN.

Witnesses: '7

T. B. HUMPHIRIES,

GEO. HJPARnnarnan 

